iPhone OS 4.0

Things to know about the iPhone OS 4.0

1. Multi-tasking

Any iPhone user will have been enraged for years that they can only perform one task at a time on their device (and this now includes iPad users as well).

Thankfully, that has changed, and in true Apple form it's been done with a slick overlay.

Basically, rather than an ugly task manager, double-tapping the home button will bring up a dock of (admittedly, only four) running applications you can switch to while staying in another app.

While this is cool in itself, Apple is taking it up a notch by using the multi-tasking element to add in some new functionality.

Location-based services and VoIP are all now included and can stay running even when you're on the move and not using them - great news for the likes of Skype.

And push just got that much bigger for Apple - while push notifications have hit 10 billion since launch last year, new 'local' notifications won't need to parse the Apple servers, thus saving batteries.

2. Apple's new Game Center

Apple has been banging on about how great its iPhone platform is for gaming, and its launched the Game Center to back it up.

Basically, it's a way of taking gaming for the iPhone from the device and into the cloud, with the launch of social networking for gaming.

This means that you can invite friends to join you in a game, or if you're up too late/a complete Billy-No-Mates then you can use the MatchMaking option to find you a gaming partner.

Additional functionality comes in the form of integrated leader boards and achievements - ways to boast about how good you are at games is kind of the reason we all play them in the first place.

Apple hinted that points might come into the achievements soon, jumping on the bandwagon Microsoft put in motion with Windows Phone 7.

3. Revolutionising the world of mobile advertising

We all wondered what Apple was doing when it quietly bought Quattro last year, a mobile advertising firm.

Well, it's become clear - it was launching iAd, to help it change the way we think about mobile advertising.

Say what you like about Jobs' lot, its made a huge success of the mobile apps market, and its taken that know-how and used it to actually make in-app advertising compelling.

Imagine you're in a general movie showtimes app, and then suddenly you see Woody from Toy Story poking his head out the bottom. 'Peel' the bottom layer up and you get an app within an app, offering you all kinds of cool things.

App developers can add in things like maps, video and e-commerce stores from these iAds, meaning a rich source of revenue that is a lot more entertaining than simply seeing boring words served against your App.

Apple has realised the potential here too - it's taking a massive 40% of the revenue for 'serving the iAds', which could be a very tidy extra income indeed.

4. Folders for your icons

Ever been left frustrated by the fact that you can 'only' have 180 icons on your home screen? Well, Folders is here to save you from that fate, giving you the ability to hoard up to 2,000 apps on your device.

It's more about organisation than anything else - making it easier to group your applications into elements like gaming, sports apps, utilities etc.

The folders themselves will auto-name, or you can call them what you like. If you don't want your partner to find your more dodgy apps, we don't recommend calling the folder 'System32' - not only is it not very Apple-like, apparently they know that it's not a real OS subfolder...

And for Jobs' final folder trick, it was shown that you can now change the background wallpaper on the iPhone. You know, like you've been able to do on phones since the dark ages.

5. The unified inbox

The iPhone has evolved slowly - too slowly, some might say, with Apple seemingly dragging its heels to make sure it has stuff to update.

But one of the problems to come out of these slow updates is the existence of so many email inboxes on people's iPhones, meaning you have to jump in and out of them to see all your mail - tricky if you're a freelancer or just an @ enthusiast.

So Apple has unified them all into one place - thankfully coinciding with the announcement you can have more than one Exchange account on its devices.

Not only will the messages appear in one central place, the conversations will now also be threaded, meaning you won't have to hop in and out of emails to see what's been said.

Attachments via Apps are also included as well - meaning you can open and manipulate elements included on email the way you want to.